The present invention relates to timepiece, i.e., clock and watch movements provided with a tourbillion, and more particularly to mysterious-type tourbillons, as will be described. The term “tourbillion” should here be taken in the broad sense, also covering systems referred to as carrousels. These movements traditionally comprise a casing and, mounted on the same, an energy source, a winding and time-setting mechanism responsible for loading the energy source, and a work train connected to the energy source and driving the tourbillion.
The tourbillion, developed by Breguet more than two centuries ago, comprises a rotatable cage, provided with a cage toothing meshing with the work train which turns it, and a time base comprising an escapement and a balance wheel, the escapement comprising a mobile, provided with a pinion engaging with a fixed wheel mounted on the casing, and with a wheel which is responsible for driving the balance wheel via a pallet fork, for example.
The tourbillion was developed to reduce the sensitivity of the watch to vertical positions. This result is obtained by turning the balance wheel with the cage over a cycle of the order of a minute. For more details in this regard, the work entitled “Theorie d'horlogerie”, ISBN 2-940025-10-X, pages 167 and 168, may be consulted.
Such a device entails high-level technical expertise, such that it is readily integrated in high-price movements designed to equip top-of-the-range watches.
Moreover, so-called mysterious watches and carriage clocks are known, in which the observer has the impression that a part of the movement or of the display means are, as it were, suspended in a transparent space, unconnected to other work or drive means in the watch or clock. A watch of this type is described in the book entitled “le grand livre des montres” ISBN 2-263-01722-4, page 70. In this watch, the hands are disposed between two glass plates, and the drive means are not visible. These means are generally constituted by transparent discs.